Impact of Noise and Nonlinearity on Analog Self- Interference Cancellation in In-Band Full-Duplex Communications

Abstract

Wireless revolution has evolved in ever-increasing demands on an already constrained wireless spectrum, driving the quest for increased bandwidths, greater channel capacity, and faster access rates. In-band full-duplexing (IBFD) is a promising technology that aims to answer this mitigation call by bolstering spectral efficiency through simultaneous same frequency band transmission and reception. However, transmitter-to-receiver leakage, or self-interference, remains the most barring frustration to IBFD realization. Therefore, self-interference cancellation (SIC) is necessary to suppress any polluting SI to a level below the receiver’s noise floor. The level of energy reduced by SIC determines the quality of the radio as well as overall system throughput. In this paper, a simulation model of an IBFD transceiver is developed in MATLAB, with inclusion of various sources of distortion. Subsequent results detailing an investigative study done on a fully adaptive tapped-branch analog self-interference canceller are shown. Evaluation of the results reveal marginal effect on the SIC efficacy due to transmission path noise and nonlinear distortion alone. However, expansion of model consideration for conceivable cancellation hardware nonlinearity reveals an indirectly proportional degradation of SIC performance by up to 35dB as distortion levels vary from −80dBm to −10dBm. These results indicate consideration of such nonidealities should be an integral part of cancellation hardware design for the preclusion of any intrinsic cancellation impediments.